The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) is undergoing final system debugging for the closed-loop fiber position system. The accuracy of the benchmark position of the fiducial fibers is a key factor affecting the closed-loop fiber position system; The more accurate the benchmark position of the fiducial fibers, the higher the accuracy of the photogrammetric system, and the accuracy of fiber position will also be improved. We have measured the position of the fiducial fibers for two consecutive years. Two laser trackers installed at different sites were used to simultaneously measure the position of the fiducial fibers on the focal plane, and the measurement result were compensated for errors using high-precision indium steel standard rods and control points. Afterwards, we conducted fusion on two sets of the laser tracker data, ultimately obtaining the position of the fiducial fibers. Compared the position of the fiducial fibers obtained from two years of measurement with the theoretical hole position of the fiducial fibers, the results showed that the average measurement accuracy of the fiducial fibers was within 200 μm. When comparing the position of the fiducial fibers horizontally, the stability difference between the two years was around 100 μm. After applying the benchmark position to the closed-loop fiber position system, the Root Mean Square Error (RMSE) value of fiber position is 16.57 μm, and the position accuracy of 97.45% fibers is within 40 μm.
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